1. Field of the Invention
This invention relates generally to electrode structures useful in electrochemical cells and, more particularly, this invention relates to a process for pressure bonding a consumable, reactive metal anode plate to a bipolar plate.
2. Description of the Prior Art
Electrochemical cells utilizing consumable, reactive metal anodes are well known. Typically, the anode comprises an alkali metal, such as lithium, in elemental, compound or complex form, in conjunction with a cathode and an aqueous or non-aqueous electrolyte. The electrolyte normally comprises an aqueous solution of lithium hydroxide.
Such cells are described in detail in numerous patents and publications, including U.S. Pat. Nos. 3,791,871 (Rowley); 3,976,509 (Tsai et al); 4,007,057 (Littauer et al); and 4,188,462 (Klootwyk), the details of the respective disclosures being incorporated herein by reference.
The anode typically is in the form of a disc, plate or other structure having at least one surface which contacts the electrolyte during operation, and an opposite surface which is bonded to a bipolar plate. The bipolar plate typically is of nickel, copper or alloys of other metals and the cathode is bonded to the opposite side thereof to form a bipolar battery plate.
Previous bonding techniques have used flat platens or presses to pressure bond a lithium foil anode directly to a mechanically abraded nickel foil bipolar plate, with a cathode plate bonded to the other side of the bipolar plate, thereby forming a battery plate for use in electrochemical cells. This method often produced a poorly bonded lithium foil anode. In some instances, the actual bonding was estimated at less than 25% of the active area. One of the major causes for such a poor bond has been the entrapment of air between the lithium foil anode and the metal foil bipolar plate.
This invention is directed to the above problems by providing a new bonding technique which ensures substantially 100% bonding of the lithium anode to the bipolar battery plate.